Operating theatre fires: Adding more oxygen to the mix

A recent review of possible dangers relating to operating theatre fires and use of high-flow nasal oxygen (HFNO) appeared in the March issue of the Australian and New Zealand College of Anaesthetists (ANZCA) Bulletin 2018. ¹ This article raised concerns of increased fire risk with HFNO during local anaesthesia and sedation techniques for head and neck surgery. The Web Based Incident Reporting System (webAIRS) from the Australian and New Zealand Tripartite Anaesthetic Data Committee (ANZTADC; https://www.anztadc.net/) project has reported two such cases involving HFNO.

The first case involved a previously well patient requiring excision of a forehead basal cell carcinoma under local anaesthesia and sedation. HFNO was administered using the Optiflow Thrive™ system (Fisher & Paykel Healthcare, Auckland, New Zealand) at 30 L/min via nasal cannula. Aqueous chlorhexidine preparation had been used to clean the area, and a swab soaked in the same solution was applied to the patient’s eyes. When diathermy was applied to the wound, a flash burn to the patient’s eyebrow occurred. A wet pack was immediately applied to the superficial burn area.

The second case was an obese patient with obstructive sleep apnoea requiring excision of a scalp lesion under local anaesthesia and sedation. Again, HFNO was administered using the Optiflow Thrive™ system at 30 L/min via nasal cannula during surgery. The patient’s head was turned, causing the drapes to gape open near the right posterior aspect of the head. After approximately one hour, the surgeon noted newly shaved hair in the area was on fire. This fire was immediately extinguished with wet swabs. Two areas of erythema related to the burnt hair developed and responded well to conservative management.

Both cases exemplify the potential of flash burns during head and neck surgery in the presence of high oxygen concentrations under certain conditions. The gaseous plume generated by the Optiflow Thrive™ system at 30 L/min is shown in Figure 1. The top photograph (Figure 1(a)) is taken using a manikin placed on an operating table in a darkened operating room with ambient lighting. It shows the plume of heated and humidified oxygen around the face using a glycol/water mixture (‘fog juice’). The middle photograph (Figure 1(b)) shows the plume when a white camera spotlight similar to an operating theatre light is used. Figure 1(c) is taken with a blue light, which provides the best definition of the plume. Although the manikin does not have a respiratory cycle, the simulated plume provides a strong suggestion that high oxygen fractions may be found well away from the patient’s head and neck region during surgery.

Figure 1.

High-flow nasal oxygen on manikin positioned on operating theatre table with a glycol/water mixture used to show extent of gaseous plume: (a) ambient lighting, (b) white camera spotlight and (c) blue light.

It is advisable that anaesthetists use the lowest FiO₂ possible to support the patient’s oxygen saturation at a safe level. Close communication between surgeons, anaesthetists and nursing staff throughout these procedures is recommended. Oxygen pooling under the drapes should be avoided by providing good airflow around the sterile area. The possible use of suction to scavenge high oxygen pockets trapped under drapes and in contact with the patient should also be considered.